Pokemon XD: Gale of Darkness Unlockables

Catch a Wooper and give it to the man in Pyrite Town. He will trade you a level 20 Larvatar.

To have a chance at snagging Lugia in the demo version, you must first snag the first 60. Then, go to the mountain with a Groundon statue and Lugia will fly there. You will them battle him. He is at level 50.

Lugia can be obtained at Nickledark Island. He comes out at level 50 after you defeat Cipher Boss Deathgold.

here are multiple ways to get the Purification Chamber at full tempo for all nine sets (chambers). Try the following:
Format: Northwest - Northeast - Southwest - Southeast
Set 1: Surskit - Nuzleaf - Hoppip - Spheal
Set 2: Sableye - Baltay - Carvanha - Flaaffy
Set 3: Teddiursa - Pidgeotto - Meowth - Hitmonlee
Set 4: NInetales - Mawile - Numel - Lunatone
Set 5: Zangoose - Kangaskhan - Togepi - Spearow
Set 6: Venomoth - Weepinbell - Swinub - Shroomish
Set 7: Magneton - Snorunt - Makuhita - Ledyba
Set 8: Parasect - Poochyena - Spinarak - Ralts
Set 9: Espeon - Hitmonchan - Duskull - Houndoom

To get the Master Ball, see Professor Kranein the Pokemon HQ lab. He is in a room on the first floor. Talk to him and he will open up a passage in the floor. There is a chest in the room. Open it to find a Master Ball. You must have been to Citadark Isle at least once to get the Master Ball. It is best used on Lugia.

Go to a shop and buy about ten Pokeballs. The shopkeeper will say "Thank you! As a bonus have a Premier Ball!".

You can get all three Johto starters. When you do Mt. Battle in story mode and complete all of it, you will be rewarded with one Johto Pokemon with their elemental hyper beam. Totodile will have Hydro Cannon. Cyndaquil will have Blast Burn. Chikorita will have Frenzy Plant. You can get all three starters by just doing Mt. Battle a total of three times.